Call function without optional arguments if they are None

Question

There\'s a function which takes optional arguments.

def alpha(p1=\"foo\", p2=\"bar\"):
     print(\'{0},{1}\'.format(p1, p2))

Let me iterat

Answer 1

I'm surprised nobody brought this up

def f(p1="foo", p2=None):
    p2 = "bar" if p2 is None else p2
    print(p1+p2)

You assign None to p2 as standart (or don't, but this way you have the true standart at one point in your code) and use an inline if. Imo the most pythonic answer. Another thing that comes to mind is using a wrapper, but that would be way less readable.

EDIT: What I'd probably do is use a dummy as standart value and check for that. So something like this:

class dummy():
    pass

def alpha(p1="foo", p2=dummy()):
    if isinstance(p2, dummy):
        p2 = "bar"
    print("{0},{1}".format(p1, p2))

alpha()
alpha("a","b")
alpha(p2=None)

produces:

foo,bar
a,b
foo,None